1. Field of the Invention
The present disclosure pertains to a system and method for controlling insufflation pressure during inexsufflation of a subject.
2. Description of the Related Art
Coughing functions to clear mucus from the airway of a subject. During a cough, inhaled air is drawn in slowly (<1 LPS). Then, the glottis closes and the expiratory muscles contract, increasing the subglottic pressure. The cough begins when the glottis opens and air is forced quickly from the lungs. The lungs continue to empty at a rate of roughly 4 LPS until the lungs are sufficiently decompressed. Some people, due to injury, disease, or thoracic surgery, find it difficult or impossible to cough effectively on their own. For these people, assisted, or artificial, airway clearance is prescribed.
Artificial airway clearance can be achieved via many methods. One such method employs the use of a mechanical in-exsufflator (MI-E). An MI-E is a medical device that delivers positive airway pressure through the mouth, nose, or a tracheostomy, gently filling the lungs to capacity (insufflation). It then abruptly reverses pressure which generates an expiratory flow, mimicking a cough (exsufflation).
In conventional systems, determining inexsufflation settings for a particular patient can be imprecise and/or inaccurate. Each patient has unique respiratory characteristics (e.g. airway resistance, lung compliance, patient effort, etc.), which can change over time and/or during the course of treatment. Usually, relying on past experience, and through trial and error, a physician may arrive at inexsufflation settings that may or may not be optimal.